LEXINGTON, Ky. -- Kentucky horse racing regulators have approved a major ban on anabolic steroids that could outlaw the drugs for next year's Kentucky Derby and other races in the state.

The Kentucky Horse Racing Commission approved the measure unanimously Monday. Gov. Steve Beshear has said he'll support an emergency order to enact the ban in time for next year's Derby.

The new rules would prohibit horses from racing with any steroid in their system. Three naturally occurring steroids would still be allowed for therapeutic purposes, but even those must be out of the horse's system by 60 days before a race.

Among the steroids banned is the drug Big Brown had in his system before winning this year's Derby.